[Successful use of methylprednisolone therapy in a case of non-herpetic acute encephalitis with antibodies against ionotropic glutamate receptor epsilon2 and delta2].

This report concerns a 32-year old man with non-herpetic acute limbic encephalitis. He was admitted to our hospital because of high fever and consciousness disturbance. Cranial MRI revealed abnormal signal intensities in the bilateral mesial temporal lobes. On the second hospitalization day, he developed status epilepticus, which necessitated general anesthesia. Following administration of intravenous (IV) methylprednisolone pulse therapy (1 g/day, 3 days), his consciousness disturbance began to improve. Treatment with high-dose IV methylprednisolone was continued for about 2 weeks, but on the 7th day, he showed severe anterograde amnesia and retrograde amnesia regarding the preceding 5 or 6 years. Subsequently, however, his amnesic disorders improved markedly, and on the 46th day, memory dysfunction had disappeared. Autoantibodies against the glutamate receptor subunits epsilon2 and delta2 were detected in both the CSF and serum, but these antibodies in the CSF became normal during the clinical course. The voltage-gated potassium channel antibody was negative. This case report indicates that high-dose IV methylprednisolone therapy may be an affective treatment for non-herpetic acute limbic encephalitis, possibly associated with autoimmune mechanisms.